Drinking containers, such as cups or mugs, which nest or stack have generally been fabricated of lightweight material for a single or limited number of uses; for example, picnics and informal parties. Stacking ability is important for storage and transport, since the single or limited use of these articles typically requires transport and storage of large numbers of articles. Stacking considerations were primarily directed toward minimizing the stack height of the containers, which resulted in larger numbers of containers for a given stack height or space toward sufficient strength when the containers are packed to withstand transport and rough handling, and toward ease of dispensing the containers for use, i.e., the containers should not stick together or be so loosely stacked, that the bottom container would fall if the stack were lifted.
However, glass tumblers are fabricated of heavier and thicker material and are used repeatedly and often in a more formal setting. Such tumblers are most frequently stored upright in a single layer on a hard surface, such as a cupboard shelf. Alternatively, a more efficient means and common method of storing glass tumblers is to "stack" them by "pyramiding," which involves stacking an upper tier of tumblers upside down, or inverted, upon a lower tier of inverted tumblers, such that each upper tumbler is supported on its rim by the base of more than one lower tumbler. This method is stable and allows drainage and drying of the tumblers. Consequently, glass tumblers are generally designed on the basis of ease of use for drinking, for repeated use, and for aesthetic appeal, and not on the basis of storage space efficiency.
Currently, the use of machine washing usually results in glass tumblers which are completely dry before they are put away for storage. Furthermore, pyramiding tumblers is not the most efficient use of space, and is thus less useful for longer-term storage and for transport of large numbers of tumblers. Recently, glass tumblers which stack in a nesting fashion have become available. However, these tumblers have been designed on the bases described above, and suffer several drawbacks. One is that the stack height is relatively high; that is, the portion of the entire length of the tumbler which nests into the lower tumbler is relatively small. Another is that the tumblers are often top-heavy, so that stacks thereof may be unstable. Yet another is that the outer surface of the side walls of the upper tumbler often touches or rests against the inner surface of the side walls of the lower tumbler, resulting in an increased likelihood of the tumblers stacking with consequent damage to and breakage of the tumblers. Yet another drawback is that the side wall surface of currently available stackable glass tumblers are often curved or angled in an upright direction, such that ornamentation of the surface of the side walls of the glass tumblers with printed or other externally applied decorative material, such as logos, is difficult if not impossible.